Seismic fragility of reinforced concrete frames with vertical irregularities

Abstract

Seismic fragility functions are essential for performance-based seismic design of structures. It is a common practice in the past to consider global demand parameters, such as peak roof displacement or drift in a building to estimate its seismic fragility. However, such global demand parameters may not suffice in case of buildings with vertical irregularities, where maximum demand is mostly concentrated at the level of irregularity. To investigate the matter, reinforced concrete frames with and without vertical irregularity (soft storey) are considered in the current study. Nonlinear dynamic analysis of the frames subjected to ground motions scaled-up for different PGA is carried out to estimate the local and global drift demands, also known as engineering demand parameters (EDPs). Seismic fragilities developed for the frames based on both the local and global EDPs are presented. Finally, the importance of component-based fragilities for irregular frames is emphasized.